A conventional winch assembly normally comprises a cable drum adapted to reel-out or reel-in a cable entrained thereon. The winch assembly further comprises an engine-driven input shaft which meshes with a pair of axially opposed bevel gears to rotate the gears in opposite directions. A friction clutch is associated with each of the gears whereby actuation of one clutch will establish a driving connection with an output shaft to effect the reel-out operation whereas actuation of the other clutch will establish a drive connection between the other gear and the output shaft to effect the reel-in operation. The output shaft is suitably connected to the cable drum via a transfer gear arrangement.
A common problem with such a conventional winch assembly occurs during the reel-in operation and when the load being reeled-in by the cable drum imposes a torque load on the output shaft which equals or is greater than the torque load imparted to the bevel gear being utilized for the reel-in operation. For example, this condition may occur when engine speed and the torque generated thereby is sufficiently reduced so that the engine cannot apply a sufficient holding torque to the bevel gear to hold or reel-in the load. Likewise, such a condition may arise upon the raising of a suspended load and when engine speed and the torque generated thereby does not provide sufficient power to lift the load.